Northern Ireland was marketed as a business destination to more than 120 Silicon Valley business bosses at a reception in the USA this week.

The delegation was told that 75% of inward investors have reinvested in Northern Ireland and that Belfast is ranked first after London for attracting foreign direct investment in the UK.

The Stormont first ministers have also officially opened the Invest NI office in San Francisco.

Companies from the west coast of America including Seagate, Concentrix, Cybersource VisaCybersource, Vello Systems and WANdisco have already established operations in Northern Ireland. In 2012-13, manufacturing exports to the Americas were worth more than £1bn.

First Minister Peter Robinson said operating costs in Northern Ireland were on average 20% to 30% cheaper than in the rest of the UK and western Europe.

"Through events like this we hope to convince many more businesses of the benefits of choosing Northern Ireland as a place to invest," he said.

"We reinforced why Northern Ireland is one of the most competitive business propositions in Europe due to our transport links, telecommunications infrastructure and the skill base."

Mr McGuinness outlined the importance of US trade missions, which have often been crgiticised.

"If you don't travel to the US and meet senior business executives, you simply don't count." he said.

"We have a talented labour force with a very strong work ethic and are well-placed to meet international business needs.

"Reinvestment by global companies sends a strong signal to the world."

The Invest NI team in the San Francisco office will primarily focus on high technology sectors on the west coast.